Development of solar heat collectors has engaged inventive minds for many years. One of the principal objectives in attempting to develop effective collector units has been to utilize the principle of parabolic reflectors in an effort to concentrate as much heat as possible from the sun rays onto a fluid conductor containing heat-transfer fluid of one kind or another. Examples of the employment of parabolic-type reflectors in prior devices are represented by U.S. Pat. Nos. 1,162,505, to Nichols, dated Nov. 30, 1915; 1,683,266, to Shipman, dated Sept. 4, 1928; and 1,880,938, to Emmet, dated Oct. 4, 1932.
In utilizing a true parabolic cross-section in a reflector for sun rays to direct the rays intensely upon a fluid conductor disposed at the focus of the reflector member, it is necessary to mount the reflector for pivotal movement either during the day or during the seasons, due to the fact that in the winter season, the sun is 231/2.degree. below the equinox or latitude angle at noon, whereas in the summer season, the sun is higher, and is approximately 231/2.degree. above the equinox or latitude angle at noon. The latitude angle also varies in accordance with the location of the installation upon the face of the earth. For example, in the temperate zone, and more specifically, in Pennsylvania, the equinox or latitude angle is approximately 40.degree. relative to the horizontal, at noon. Therefore, in an effort to compensate for this situation, the aforementioned patents to Nichols and Shipman have provided pivotal mountings for the reflector member.
Another attempt to cope with the situation referred to above comprises U.S. Pat. No. 3,321,012, to Hervey, dated May 23, 1967. It will be seen that this patent utilizes a reflector system which is semi-circular in cross-section and employs a tubular conductor which is flat and substantially rectangular in cross-section and is positioned substantially radially with respect to the reflecting surface of the reflector member for purposes of attempting to increase the contact area for radiation. Also, the present inventor obtained U.S. Pat. No. 2,969,788, dated Jan. 31, 1961, in which pairs of reflector members were positioned with respect to fluid-circulating tubes with the reflector members which, in cross-section, are curved somewhat in a parabolic manner but pairs of such curved sections are used inversely to a parabolic arrangement and, further, these reflector members are mounted for pivotal adjustment to render the same movable during different times of the day in an effort to achieve maximum reflection of the sun rays onto the fluid-containing tubes.
In general, it also appears to be the tendency in prior developments of solar heat collectors to dispose the conducting tubes substantially vertically or at least disposed in vertical planes when in use, there usually being horizontal manifolds extending along the upper and lower ends of the tube to effect circulation of fluid therethrough. Depending upon how the fluid is circulated in said tubes, drainage problems sometimes exist when it is desired to drain the system for any reason.
In accordance with the present invention, it now has been found that there are areas of improvement which do not appear to have been explored or developed previously, these improvements being directed toward the simplification of the reflector members in particular, as well as the cross-sectional shape of the fluid-conductor system, details of which are set forth below.